1. Field of the Invention
The present invention relates to telecommunication systems. More particularly, the present invention relates to a system and method for providing aggregated power from a plurality of subscriber devices via respective communication lines to a network element for powering the network element.
2. Background Information
Public telecommunication systems include subscribers who are coupled to a telecommunications network with a twisted pair wire loop, commonly known as a subscriber loop. Digital transmission systems based on local subscriber loops are generally called Digital Subscriber Loops (DSLs). Line codes of various formats are used to convey digital data over existing twisted-pair copper telephone lines connecting the telephone company Central Office (CO) to subscribers. Conventional DSL data modems are designed to provide service to a percentage of customers at a prescribed data rate. As used herein, the term “xDSL” refers to the different variants of DSL technologies for transmitting high-bandwidth information over twisted-pair (i.e., copper wire) telephone lines, including, for example, Asymmetric Digital Subscriber Line (ADSL), including Asymmetric Digital Subscriber Line Version 2 ADSL2) and Asymmetric Digital Subscriber Line Version 2+ (ADSL2+), All Digital Loop ADSL (ADL ADSL), Symmetric Digital Subscriber Line (SDSL), High Bit-rate Digital Subscriber Line (HDSL), Very High Bit-rate Digital Subscriber Line (VDSL), Rate Adaptive Digital Subscriber Line (RADSL), Universal Digital Subscriber Line (UDSL), Consumer Digital Subscriber Line (CDSL), G.Lite (an easier-to-install form of ADSL, also referred to as splitterless ADSL) or DSL Lite (another acronym used for an easier-to-install form of ADSL, or splitterless ADSL), Integrated Services Digital Network Digital Subscriber Line (IDSL), and any other variant of DSL, such as, for example, Error Correction Asymmetric Digital Subscriber Line (EC-ADSL), Single-Pair High-Speed Digital Subscriber Line (SHDSL), Enhanced Single-Pair High-Speed Digital Subscriber Line (ESHDSL), 10 Mb/s Digital Subscriber Line (10MDSL), Multi-Megabit Digital Subscriber Line (M2DSL), Broadband Digital Subscriber Line (BDSL), and Multi-Megabit Multi-loop DSL (MMDSL).
To interconnect multiple xDSL users to a high-speed backbone network, the telephone company can use various types of network equipment, such as, for example, a Digital Subscriber Line Access Multiplexer (DSLAM). The DSLAM can connect to, for example, an asynchronous transfer mode (ATM) network that can aggregate data transmission at gigabit data rates. At the other end of each transmission, the DSLAM demultiplexes the signals and forwards them to appropriate individual xDSL connections (subscribers). Traditionally, such network equipment has been powered from the CO, as a result of the historical telecommunication network architecture of large, but fairly sparse, concentrations of equipment housed in the COs. However, the CO is evolving from a telecommunications transport hub into a business and management center for a highly diffuse and interconnected network of comparatively numerous, small and remote transport hubs (network elements such as, for example, Remote Terminals or RTs).
Conventionally, the RTs have been powered by a local utility drop, i.e., a power feed from the electric utility company (e.g., via a connection to a power line, wall outlet or the like) to the RT. However, such a configuration requires the need to negotiate, pay for the installation of, and support monthly charges for the local utility drop to the RT.
An alternative to a local utility drop for supplying power to remote equipment, such as RTs, is the use of loop powering from the CO. Such a loop powering scheme typically entails running between one and 24 subscriber loops from the serving CO to the RT, and using at least one of the subscriber loops to provide the subject RT with, for example, a 60 milliamp current source with an open circuit voltage of as much as 350 volts (+/−approximately 175 volts relative to earth). Such a loop powering scheme is very inefficient, as up to 50% of the supplied power can be lost in transit. Such a loop powering scheme also results in the loss of pair use and decreased bandwidth, as the subscriber loop pair being used for powering the RT is not used for communication. Additionally, concomitant safety issues result from the high voltages involved, e.g., for the workers who have to service the RTs being supplied with such high voltages.
For given receiver noise conditions, higher channel capacity over copper pairs is achieved primarily by limiting length, and employing as large a gauge wire as possible. For a given maximum operating voltage, the same factors can contribute to increased power transport capability. However, the closer the RTs are moved to the subscriber to improve service bandwidth, in general, the farther it is between the serving CO and the RT. Consequently, the problem of delivering more power from the CO to broader bandwidth equipment is compounded.